Paper Reading #29: Usable gestures for blind people: understanding preference and performance

Usable Gestures for Blind People: Understanding Preference and Performance

Authors - Shaun K. Kane, Jacob O. Wobbrock, and Richard E. Ladner


Authors Bios - Shaun K. Kane is an Assistant Professor at the University of Maryland and received his PhD from the University of Washington.
Jacob O. Wobbrock is an Associate Professor at the University of Washington specializing in human-computer interaction.
Richard E. Ladner is a Professor at the University of Washington and has a PhD in mathematics from the University of California, Berkeley.


Venue - This paper was presented at the CHI '11 Proceedings of the 2011 annual conference on Human factors in computing systems.


Summary


Hypothesis - In this paper, researchers question the design of touch screen interfaces for smartphones as they relate to their use by both blind and sighted people. The hypothesis is that blind and sighted people have different perceptions as to how touch screen gestures should work and also have different ways of performing similar gestures. Knowing these differences could help designers in the future be more aware of how their applications are going to be used.


Methods - 1) 10 blind and 10 sighted participants were asked to take part in the first study that asked them to perform 2 possible gestures to perform a specific action that was read by a moderator. The gesture was performed and recorded on a Lenovo tablet PC and the participants were encouraged to explain their gesture as they performed it. After creating the gestures, participants were asked to rate the effectiveness of their gestures on a Likert scale.
2) The second study consisted of the same setup as the first and used the same participants only this time they were all asked to perform the same gestures for certain actions and rate them on a Likert scale.


Results - 1) The only significant difference on all the Likert data was that blind people found their gestures to be better matches then sighted people overall. Gestures created by the blind people had significantly more strokes and used the edges and corners of the screen more than the sighted people. Gestures created by the blind people were also significantly more likely to use multi-touch and most of those used a mode key by holding a finger in an area while performing a gesture with the other hand. Text-entry produced mixed results with QWERTY keyboard being the preferred method by both blind and sighted participants.
2) There was no overall difference in easiness for blind and sighted participants but their was a significant difference between categories meaning the gestures in one category were easier to perform than those found in another category. There was also significant interaction between blindness and gesture category meaning categories carried different easiness ratings between blind and sighted people. Some other noticeable differences were bigger gestures done by blind people, faster gesturing by sighted people, and greater likeliness of gesture recognition of gestures created by sighted people but gestures created by the blind participants were recognized more accurately than those done by sighted users. 


Content - The researchers narrowed down the results of their studies to the following design guidelines:

• Avoid symbols in print writing - Many blind people never learn to print and using writing as a form of input would alienate these people
• Favor edges, corners, and other landmarks - These locations are easily found without the use of sight
• Limit time-based gestures - Blind people tend to perform gestures at a different pace than sighted people so limiting gestures is not practical
• Reproduce traditional layouts when possible - Using layouts such as the QWERTY keyboard help to immediately familiarize users with an interface

Conclusion - The researchers conclude by stating that the research presented in this paper will help lead to better touch screen designs that can be used by both blind and sighted users.


Discussion


I think the researchers achieved their goal of exploring differences in how blind users operate touch screen interfaces. I think this research is important as it attempts to close gaps that technology have for the most part ignored such as those with disabilities. It was interesting that whenever gestures performed by blind people were recognized they were more accurately recognized than gestures made by sighted people.